The biogenesis of mitochondria in Baker's yeast will be studied. Particular emphasis will be placed on the mechanism of transport and integration of cytoplasmically synthesized proteins into the organelle. Toward this end, two major lines of investigation will be taken. 1) We will attempt to establish the role of mitochondria-bound 80S cytoplasmic ribosomes in the transport of proteins into mitochondria. This will be attempted, in part, by a) systematic comparison of the products of mitochondria-bound and free cytoplasmic ribosomes and the mRNA, translated in vitro, extracted from these polysomes. b) The mode of assembly and binding of mitochondria-bound 80S polysomes to the outer mitochondrial membrane. 2) Starting with a kinetic approach, we will search for cytoplasmically synthesized mitochondrial proteins which are completed in the cytoplasm prior to their transport into mitochondrion. Attempts will be made to search for possible precursor forms to these proteins which may function in the transport process. Attempts will be made to reconstruct transport processes in vitro. Finally, recently discovered soluble products of mitochondrial protein synthesis will be investigated. We will attempt to characterize these products to learn if they are exported from mitochondrion and if they are associated with other proteins as complexes. The long term objective in these studies is to elucidate the function of these novel products of mitochondrial protein synthesis.